Locking mechanism for stapler paper presser table

ABSTRACT

Immediately after a clinch lever causes a clinch link to clinch the leg of a staple which penetrates sheets of paper to be stapled, a pressure by the clinch lever with respect to the clincher link is temporarily reduced by a pressure reducing unit. Therefore, a clincher moves down in a state where the clincher still receives the press-contacting force from a driver plate. Accordingly, the looseness occurs between the driver plate and the clincher link. A fixing plate becomes easy to draw out as much as the looseness. If the fixing plate is set to be drawn out at this timing, it can be simply drawn out to be moved to the initial position.

TECHNICAL FIELD

The present invention relates to a paper-pressing table lock mechanismof stapler for fixing a table, on which sheets of paper to be stapled isset, in a paper-pressing state and releasing the fixing immediatelyafter clinching each leg of a staple penetrating the sheets of paper.

BACKGROUND ART

In order to staple sheets of paper, a general stapler strongly pressesand clamps the sheets of paper between a stapling table and a unit fordriving a staple. After this state is fixed, a staple is driven so as topenetrate the sheets of paper, and each leg of the staple is thenclinched by a clincher.

Such a lock mechanism has been disclosed in JP-B2-2688114, for example.

As shown in FIG. 4 of JP-B2-2688114, a fixing pin 39 is engaged with abow-shaped slot 38 of a fixing plate 36 and the diameter of curvature ofthe slot 38 increases, thereby causing a wedge action between the wallof the slot 38 and the fixing pin 39. Such a wedge action fixes astapler head 12 in an operation position so as not to be vibrated up anddown by a rotation of a rotating pin 13.

However, since a frictional resistance between a wall of the slot 38 andthe fixing pin 39 is significantly large when the wedge action occursbetween them, plenty of energy is needed to rotate the fixing plate 36in the original position after the fixing. Therefore, when the fixingplate 36 is rotated by a force of a spring, a strong spring is needed,and when the fixing plate 36 is rotated by electricity, much electricpower is needed.

DISCLOSURE OF THE INVENTION

In order to solve the above-mentioned problems, it is an object of thepresent invention to provide a paper-pressing table lock mechanism of astapler which can easily draw out a fixing plate by temporarily reducinga force for clinching a staple immediately after each leg of the stapleis clinched.

In order to attain the object, a paper-pressing table lock mechanism ofa stapler of the present invention is provided with a table link that isrotatably provided in a base and has a paper-pressing table including amovable clincher on the leading end thereof, the table link having afixing pin projecting on the side surface thereof; a fixing plate thatis provided so as to slide with a wedge action with respect to thefixing pin and that is engaged with the fixing pin to lock the tablelink in a paper-pressing state; a driver that holds sheets of paper tobe stapled, which is pressed against the table, and push up a staplefrom the opposite side toward the table; a clincher link that isrotatably provided in the base so as to press the movable clincher ofthe table link in the paper-pressing state from the opposite side to thedriver and that clinches each leg of the staple penetrating the sheetsof paper to be stapled; a clinch lever that presses the clincher link tooperate; and a pressure reducing mechanism that temporarily reduces thepressure by the clinch lever with respect to the clincher link.

It is preferable that the pressure reducing mechanism is a sector-shapedcam of which the periphery is engaged with the clinch lever, and astepped portion with respect to the clinch lever is formed on theperiphery of the sector-shaped cam. When the clinch lever is engagedwith the stepped portion, the pressure with respect to the clincher linkmay be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically illustrating a table lockmechanism and a clincher mechanism.

FIG. 2 is a perspective view of the table lock mechanism.

FIG. 3 is a diagram illustrating the side of the table lock mechanismbefore operation.

FIG. 4 is a diagram illustrating the side of the table lock mechanismwhen papers are pressed.

FIG. 5 is a diagram illustrating the side of the table lock mechanism atthe time of table-locking.

FIG. 6 is a perspective view of the clincher mechanism.

FIG. 7 is a diagram illustrating the side of the clincher mechanismbefore operation.

FIG. 8 is a diagram illustrating the side of the clincher mechanismbefore clinching.

FIG. 9 is a diagram illustrating the side of the table lock mechanism atthe time of clinching.

FIG. 10 is a diagram explaining a state where the looseness occurs in aclincher link.

FIG. 11 is a diagram explaining an operation of the clincher mechanism.

FIG. 12A is a diagram explaining the positional relationship between aclinch cam and an engagement pin at the time of clinching.

FIG. 12B is a diagram explaining the positional relationship when thepressure is reduced.

FIG. 13 is a diagram explaining the positional relationship between theleft and right clinch cam when the phase between the concave sections 35are shifted.

FIG. 14 is a diagram explaining the positional relationship between theleft and right clinch cam when the phase difference is about 15°.

In the drawings, reference numeral 3 represents a table link, referencenumeral 5 represents a fixing plate, reference numeral 8 represents atable, reference numeral 13 represents a fixing pin, reference numeral25 represents a clincher link, reference numeral 26 represents a clinchlever, reference numeral 27 represents a clinch cam, reference numeral34 represents a circular arc section, and reference numeral 35represents a stepped portion.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a perspective view of an embodiment of the present invention,illustrating a table lock mechanism A and clinch mechanism B of anelectric stapler. The table lock mechanism A, which presses a table 8against sheets of paper (a) to be stabled when the sheets of paper (a)to be stapled is set in a predetermined position, is composed of a tablelink 3, a return link 4, a fixing plate 5, a table fixing link 6, and afixing cam 7. On the other hand, the clinch mechanism B, which pushes upa staple into the sheets of paper (a) in a state where the sheets ofpaper is pressed (hereinafter, referred to as ‘the paper-pressingstate’), and clinches each leg of the staple which has penetrated thesheets of paper (a) by the pushing up, is composed of a clincher link25, a clinch lever 26, and a clinch cam 27.

Next, the table lock mechanism will be described sequentially withreference to FIGS. 2 to 5. Reference numeral 10 denotes abase plate inwhich both mechanisms are provided. Two sheets of base plates areprovided parallel to each other. Further, a stapling table 1 is fixed tothe upper portion of the front portion of the base plate 10. A driver 2,provided to move along a substantially straight line from the lower sideof the stapling table 1 toward the upper side, is driven to push up astaple on the sheets of paper (a) pressed against the table 8. The tablelock mechanism, clinch mechanism, and driver driving mechanism areoperated by the same motor. In addition, the staples are sequentiallysupplied to the table 8 in a state where each leg thereof is upward.

The table link 3 is substantially Z-shaped. On the front end thereof,the table 8 is provided, and the back end thereof is rotatably supportedby receiving a projecting shaft 9 into a bearing provided on the rearupper portion of the base plate 10. The table 8 has a movable clincher12 (refer to FIG. 1) which presses the upper portion of the sheets ofpaper (a) set on the stapling table 1 and clinches each leg of thestaple penetrating the sheets of paper (a). In addition, on the side ofthe table link 3, a fixing pin 13 is formed, protruding beyond the tablelink. The table link 3 and a clincher link to be described below arebiased together by a spring (not shown) so as to rotate downward.

The return link 4, which moves the downward-rotating table link 3upward, is disposed so as to be engaged with the fixing pin 13. A sidepin 14 of the return link 4 is engaged with a circular arc groove 15formed on the base plate 10 by a cam (not shown). The return link 4 canreciprocate in the range where the pin 14 moves within the circular arcgroove 15, centered on a projecting shaft 16 supported by the base plate10.

The fixing plate 5 has a convex portion 18 which is engaged with a guidegroove 17 formed on the base plate 10. The lower surface of the fixingplate 5 is formed obliquely so that the front portion thereof is moreseparated with respect to the guide groove 17 than the back portionthereof. Such a structure allows the fixing plate 5 to slide in a wedgeshape with respect to the fixing pin 13. In addition, on the front endof the fixing plate 5, a pin 19 is formed.

The table fixing link 6 has the middle portion formed to be bent. On theupper end of the table fixing link 6, a split groove is formed to beengaged with the pin 19 of the fixing plate 5. In the vicinity of thelower end of the table fixing link 6, a pin 20 is provided, and thelower end is provided so as to rotate about a protruding shaft 23provided on the base plate 10. In the lower end of the projecting shaft23, a spring 21 is mounted to bias the fixing plate 5 so that the fixingplate 5 always rotates in the clockwise direction of FIG. 3.

The fixing cam 7 is integrally fixed to a driving shaft 22 for drivingthe driver 2 and is engaged with the pin 20 of the table fixing link 6.

According to the table lock mechanism, if the sheets of paper to bestapled (a) is set on the stapling table 1 and the motor of the electricstapler is activated, the table link 3 rotates in the counterclockwisedirection to move downward as shown in FIG. 4, and the table 8 thereofstrongly presses the sheets of paper (a). Further, the return link 4rotates in the clockwise direction to allow the rotation of the tablelink 3. In addition, as shown in FIG. 5, the cam 7 also rotates,however, at this time, the pin 20 of the table fixing link 6 is engagedwith the periphery, which is close to the center of the fixing cam 7Therefore, since the table fixing link 6 is rotated in the clockwisedirection by a spring force, the fixing plate 5 slides in a wedge shapealong the guide groove 17, and the lower surface thereof is engaged withthe upper portion of the fixing pin 13 of the table link 3. Accordingly,the table link 3 is locked so as not to move upward. As a result, thetable link 3 is locked in a state where the table 8 strongly presses thesheets of paper to be stapled (a).

FIGS. 6 and 7 are a perspective view and a diagram showing the clinchmechanism, which is composed of the clincher link 25, the clinch lever26, and the clinch cam 27, as described above.

The clincher link 25 has a clincher pressing section 28 in the front endthereof. Its middle portion is supported to freely rotate in clockwiseand counterclockwise direction about a shaft 29 provided in the middleportion of the table link 3, and the rear portion is formed as a leg 30which is bent in an obtuse angle. On the rear end of the leg 30, anengagement portion 31 is formed to be substantially downward. When theclincher link 25 rotates in the counterclockwise direction of thedrawing, the clincher pressing section 28 presses the movable clincherof the table link 3 to operate. Since the shaft 29 moves up and down asthe table link 3 rotates, the whole clincher link 25 also moves up anddown together with the shaft.

The clinch lever 26 is provided to rotate in clockwise andcounterclockwise direction about a support shaft 32 provided in thelower portion of the base plate 10. The leading end of the clinch leveris formed in a substantially circular arc shape and is disposed so as tobe engaged with the engagement portion 31 of the clinch link 25. Inaddition, an engagement pin 33 is formed at the substantial center ofthe clinch lever 26, protruding beyond it.

The clinch cam 27 is a sector-shaped cam, that is, of which the overallfeature has a sector shape. The right and left pair of base portions ofthe clinch cam 27 are fixed to a driving shaft which is linked to amotor. Further, a circular arc portion 34 that defines periphery isengaged with the engagement pin 33 of the clinch lever 26.

According to the clinch mechanism, when the table link 3 rotatesdownward to press the sheets of paper a as described above, the clincherlink 25 does not simultaneously rotate, keeping its position. At thistime, the leg 30 of the clincher link 25 becomes free from the clinchcam 27 in a state where it is disengaged from the clinch lever 26, asshown in FIG. 8. Next, in the above-described paper-pressing state, thedriver 2 for pushing up a staple is driven from the lower side, a staple11 is pushed up from the stapling table 1 toward the sheets of paper(a), and each leg 11 a of the staple 11 penetrates the sheets of paper(a) so as to protruding beyond the rear side of the paper, as shown inFIG. 11. After that, in order for the circular arc portion 34 of therotated clinch cam 27 to push the engagement pin 33 of the clinch lever26 as shown in FIG. 9, the clinch lever 26 rotates in the clockwisedirection, and its leading end is engaged with the engagement portion 31of the clincher link 25 so as to press the engagement portion 31.Therefore, the clincher link 25 rotates in the counterclockwisedirection, and its pressing section 28 presses the movable clincher 12of the table link 3 so as to operate, which has been in thepaper-pressing state. Then, as shown in FIG. 11, each leg 11 a of thestaple 11, which has penetrated the sheets of paper (a), is clinched,and the stapling operation is completed. Therefore, the fixing plate 5which has been in the state of FIG. 5 is drawn by the fixing cam 7 so asto move to the initial position, and the table link 3 also returns tothe initial position.

As shown in FIG. 11, however, the clearance between the leading end ofthe driver 2 and the table 8 of the table link 3 becomes larger as muchas the thickness of the leg 11 a when the movable clincher 12 operatesto clinch the leg 11 a than when the driver 2 is driven, in order thatthe leg 11 a of the staple penetrates the paper, and a press-contactingforce of the fixing pin 13 with respect to the fixing plate 5 increases.Therefore, a strong force is needed to draw out the fixing plate 5 inthis state. Accordingly, if the press-contacting force of the clincher12 with respect to the driver 2 is temporarily reduced (may be released)by escaping the movable clincher 12 in a state where the movableclincher 12 still receives the press-contacting force from the driver 2,the force which pushes up the driver 2 is relaxed so that the loosenessbetween the driver 2 and the clincher link 25 occurs. An amount oftightening with respect to the staple 11 is reduced as much as thelooseness, and the fixing plate 5 is easy drawn out.

Subsequently, as a pressure reducing mechanism which temporarily reducesthe pressure by the clinch lever 26 with respect to the clincher link25, a pressure reducing unit is provided. The pressure reducing unit isconstructed with an stepped portion (concave section) 35 with respect tothe engagement pin 33 of the clinch lever 26, which is formed on thecircular arc section 34 of the clinch cam 27. The stepped portion 35 isformed in a portion slightly shifted from the end of the circular arcsection 34. When the engagement pin 33 of the clinch lever 26 is engagedwith the stepped portion, the pressure of the clinch lever 26 withrespect to the clincher link 25 is reduced. At this timing, the fixingplate 5 is set to be drawn out.

In this structure, if the clinch cam 27 rotates so that the engagementpin 33 moves to the position corresponding to the concave section 35 asshown in FIG. 12B immediately after the engagement pin 33 of the clinchlever 26 is pushed out by the end portion of the circular arc section 34so as to clinch the leg of the staple as shown in FIG. 12A, theengagement pin 33 of the clinch lever 26 sinks into the concave section35. Therefore, as shown in FIG. 10, the press-contacting force of theclinch lever 26 with respect to the clincher link 25 is reduced in thedirection of an arrow. Therefore, by pushing up the movable clincher 12in order for the force against the driver 2 is reduced, the loosenessbetween the driver 2 and the clinch link 25 occurs. Since the amount oftightening with respect to the staple is reduced as much as thelooseness, the fixing plate 5 can be simply drawn out to be moved to theinitial position.

In the above-described pressure reducing unit, the left and right clinchcams 27 are formed in the same external feature and are mounted on adriving shaft so as to rotate in the same phase. However, the externalfeature of the right clinch cam 27 and the external feature of the leftclinch cam 27 may be formed to be different from each other so that thephase between the concave sections 35 of the right and left clinch cams27 is shifted as shown in FIG. 13. In addition, the left and rightclinch cams 27 may be mounted on a driving shaft so that the phasedifference between the left and right clinch cams 27 occurs (forexample, about 15°). See FIG. 14. In this case, the engagement pin 33 ofthe clinch lever 26 sinks into the respective concave sections 35 withthe time difference between the left and right (the timing between theleft and right is shifted). Therefore, the reduction in thepress-contacting force with respect to the clincher link 25 is performedseparately in the left and right.

In addition, the pressure reducing unit is not limited to the unit usinga sector-shaped cam. For example, the rotation shaft of thesector-shaped cam itself may be moved in the stepped direction.

INDUSTRIAL APPLICABILITY

In the paper-pressing table lock mechanism of a stapler according to thepresent invention, immediately after the clinch lever causes the clinchlink to clinch the leg of the staple which penetrates the sheets ofpaper to be stapled, the pressure by the clinch lever with respect tothe clincher link is temporarily reduced by the pressure reducing unit.Therefore, the clincher moves down in a state where the clincher stillreceives the press-contacting force from the driver plate. Accordingly,the looseness occurs between the driver plate and the clincher link. Thefixing plate becomes easy to draw out as much as the looseness. If thefixing plate is set to be drawn out at this timing, it can be simplydrawn out to be moved to the initial position.

In addition, when the clinch lever is engaged with the stepped portionof the sector-shaped cam, the pressure with respect to the clincher linkcan be reduced. Therefore, the fixing plate can be easily drawn out by asimple structure.

1. A paper-pressing table lock mechanism of a stapler comprising: atable link rotatably provided in a base; a paper-pressing table providedon the table link; a movable clincher provided on a leading end of thepaper-pressing table; a fixing pin projecting on a side surface of thetable link; a fixing plate linearly slidable with respect to the fixingpin and engagable with the fixing pin to lock the table link in apaper-pressing state; a driver that drives a staple to sheets of paperto be stapled pressed against the paper-pressing table; a clincher linkthat is rotatably provided in the base so as to press the movableclincher of the table link in the paper-pressing state from an oppositeside of the driver and that clinches each leg of the staple penetratingthe sheets of paper to be stapled; a clinch lever that presses theclincher link; and a pressure reducing mechanism that temporarilyreduces the pressure by the clinch lever with respect to the clincherlink; wherein the table link and the fixing plate are separate members,and the table link and the fixing plate are relatively movable to eachother.
 2. The paper-pressing table lock mechanism of a stapler accordingto claim 1, wherein the pressure reducing mechanism comprises asector-shaped cam, and a periphery of the sector-shaped cam is engagedwith the clinch lever, the sector-shaped cam has a stepped portionformed on the periphery of the sector-shaped cam, and when the clinchlever is engaged with the stepped portion, a pressure with respect tothe clincher link is reduced.
 3. The paper-pressing table lock mechanismof a stapler according to claim 2, wherein the sector-shaped camcomprises a first and second sector-shaped cams, the first- and secondsector-shaped cams have the same external feature, and the first andsecond sector-shaped cams are mounted on a common driving shaft so as torotate at the same phase.